Sewing machine thread spool unwinder



Feb. 25, 1964 w. J. EDWARDS 3,122,113

SEWING MACHINE THREAD SPOOL UNWINDER Filed Jan. 2, 1962 will!" u INV EN TOR.

William J. Edwards WITNESS Fig. 3 BY A TTORNE Y United States Patent 3 122,113 SEWING MAQHINE THREAD SPOOL UNWENDER William J. Edwards, Denvilie, N.J., assignor to The Singer Company, a corporation of New Llersey Filed Jan. 2, 1962, Ser. No. 163,413 2 Claims. (Cl. 112-218) This invention relates to sewing machine needle thread supply spool supports, and more particularly, to a novel thread unwinding device for use with a sewing machine needle mread supply spool support.

It is an object of this invention to provide a thread unwinding device for use with a sewing machine needle thread supply spool support which will ensure unwinding of the thread axially from the spool without imparting rotation to the spool.

Another object of this invention is to provide a thread spool unwinding device of the above character which by selective positioning relatively to the spool support may accommodate a range of spool sizes.

Still another object of this invention is to provide a thread spool unwinding device which may be manufactured as an integral molded unit and which may be applied frictionally to the sewing machine spool pin without the use of fastening devices requiring operator manipulation or the use of tools.

In the accompanying drawings of a preferred embodiment of this invention:

FIG. 1 represents a side elevational view of a portion of the top cover plate of a sewing machine casing including a thread spool support and having the thread spool unwinding device of this invention illustrated as applied to a thread spool of small diameter,

FIG. 2 represents a side elevational view of a top cover plate of a sewing machine casing as in FIG. 1 but illustrating the thread spool unwinding device of this invention as applied to a thread spool of large diameter,

FIG. 3 is an enlarged end elevational view of the thread spool unwinding device of this invention, and

FIG. 4 is a cross sectional view of the thread spool unwinding device taken substantially along line 44 of FIG. 3.

Referring to FIGS. 1 and 2, 11 indicates a portion of the top cover plate of a sewing machine casing which may be formed with a central depression 12. Toward one end of the depression rises a standard 13 to which is aflixed one end of a cylindrical spool pin 14, the free end preferably being rounded as at 15.

The spool pin 14 is adapted to accommodate a selected spool of thread such as the small spool 16, illustrated in FIG. 1, or the large spool 17, illustrated in FIG. 2, from which the thread T is directed toward the sewing machine stitch forming instrumentalities through a thread guiding aperture 18 formed substantially coaxially of the spool pin in thread guide post 19 afi'ixed on the top cover r plate 11.

It is conventional in family sewing machine construction to provide for support of the supply thread spool so as to unwind the thread tangentially from the spool causing the spool to turn during unwinding. With modern family sewing machines this conventional spool supporting arrangement has become increasingly disadvantageous particularly since larger amounts of thread are now required in shorter periods of time than heretofore. Not only is a tangential thread unwind disadvantageous because of the increased resistance and consequent increased thread tension due to the inertia forces incident to turning the spool, but serious problems of thread snarling and thread breakage are encountered because of overspinning of the spool and consequent spilling of the thread.

With commercial sewing machines used in the garment 3,122,113 Patented Feb. 25, 1954 'ice trades, thread supply spools adapted to be unwound axially are quite well known. The constructions used with commercial sewing machines, however, are not well adapted for family sewing machine use for several reasons. Commercial sewing machines commonly utilize standardized size thread spools; and when the thread is to be axially unwound it is frequently wound on conical cops specifically for this purpose. Family sewing machines must be adapted to accommodate a wide variety of sizes of wooden thread spools which are traditionally adapted for tangential unwinding. An operator of a com mercial sewing machine is almost invariably a skilled and supervised technician while a large segment of family sewing machine users are quite unfamiliar with the sewing machine, use it sporadically and are not mechanically inclined. The complicated thread stands and cop unwinders used commercially are not adapted, therefore to use with family sewing machines.

Moreover, the wooden spools 16, 17 upon which practically all thread used on family type sewing machines is wound are not, in and of themselves, well adapted for axial unwinding. The side flanges of such wooden spools are not well finished and most are purposely slotted to provide an anchorage for the end of thread wound thereon. Attempts simply to unwind the thread axially over one side flange of such thread spools will result in abrading and snagging of the thread or will develop sufiicient friction therebetween to cause the spool to turn as in tangential unwinding.

The thread unwinder of this invention requires no more skill in its use than is required to place the spool on the spool pin, it is an integral unit having no detachable parts which might become lost or mislaid, and with its use thread spools of all sizes commonly used with family sewing machines may be unwound axially.

As illustrated in FIGS. 3 and 4, the unwinding device comprises an integral, substantially frusto-conical, member 20 of which the side surface 21 is slightly concave rather than perfectly frusto-conical in order to provide for contact of the thread with only the rounded edges 22 and 23 at each end. An axial bore 24 formed in the member 20 accommodates the spool pin 14.

Formed at each end of the frusto-conical member 20 are shallow counterbores 25 and 26 each slightly less in diameter than the adjacent rounded edges 22 and 23. The counterbores 25 and 26, moreover, difier in depth substantially in a direct proportion to their diameters. Preferabl the dimensions of the counterbores 25 and 26 are chosen one to envelope the flange of the largest spool commonly used with family sewing machines, i.e., approximately 1 /2" diameter and depth, and the other to envelope a flange of an intermediate sized thread spool, i.e., approximately 1" diameter and $5 depth.

Formed in the counterbore 25 of largest diameter is an undercut recess 27 within which is snapped a G-shaped wire spring of which the body portion 28 seats in the recess 27 and the inturned free extremity 29 protrudes into the bore 26 for frictional engagement with the spool pin 14 when the unwinding member 20 is placed thereon.

As illustrated in FIGS. 1 and 2, the unwinding member 20 may be placed on the spool pin 14 either end toward the spool with the rounded free extremity 15 of the spool pin facilitating introduction of the spool pin past the spring 29. With either a large or a small spool, therefore, the spool flange will be encompassed within one or the other of the counterbores 25, 26 and the thread will be directed over one or the other of the rounded edges 22, 23 only slightly exceeding the diameter of whatever spool flange is being used. The thread will not contact the unfinished slotted wooden spool flange and the thread will not be directed any great distance radially outward'beyond the spool flange which would encourage tangential unwindin. The unwinding member 20 is preferably moved on the spool pin snuggly against the spool and by virtue of the spring 29 provides for frictional resistance to turning of the spool further to encourage axial unwinding of the thread.

The spool pin 14 is preferably made sufliciently long as to accommodate the thread unwinding member 20 plus the largest spool commonly used with family sewing machines. A spool pin length of 3%" is preferable. However, it is pointed out that since the spring 28, 29 is located adjacent to the counterbore 25 of largest diameter which will occupy a position contiguous to the spools of largest size, as illustrated in FIG. 2, a spool pin of shorter length might be used if desired.

Having thus set forth the nature of the invention, what I claim herein is: v

l. A sewing machine thread spool unwinding device comprising a right circular member formed with an axial bore and circular end portions of difierent diameter each disposed substantially perpendicular to said axial bore, an exterior surface having a concave indentation formed on said member between said circular end portions, each of said circular end portions being formed with a shallow counterbore, said counterbores having diameters which diifer in substantially the same proportion as the diameters of the respective circular end portions in which said counterbores are formed, one of said counterbores being formed adjoining'said axial bore with an undercut circular recess, a circularly formed wire spring seated in said undercut recess and a free extremity of said wire spring projecting into said axial bore.

2. Sewing machine thread spool unwinding means comprising a free-ended cylindrical thread-spool supporting pin carried on said sewing machine, a thread guide carried on said sewing machine substantially axially beyond the free end of said spool supporting pin, a right circular member formed with an axial bore slidably accommodating said spool pin and being formed with circular end portions of different diameter each disposed substantially perpendicular to said axial bore, an exterior surface formed with a concave indentation formed on said member between said circular end portions, each of said circular end portions being formed with a shallow spool flange accommodating counterbore, said counterbores having diameters which difier in substantially the same proportion as the diameters of the respective circular end portions in which said counterbores are formed, one of said counterbores being formed adjoining said axial bore with an undercut circular recess, a circularly formed wire spring seated in said undercut recess and a free extremity of said wire spring biased toward a position projecting into said axial bore for engaging said spool supporting pin frictionally to maintain said member in selected position on said spool supporting pin.

References Qited in the file of this patent UNITED STATES PATENTS 1,367,387 Hayes Feb l, 1921 1,783,339 Mitchell Dec. 2, 1930 3,043,536 Brame et al. July 10, 1962 FOREIGN PATENTS 379,513 Great Britain Sept. 1, 1932- 

1. A SEWING MACHINE THREAD SPOOL UNWINDING DEVICE COMPRISING A RIGHT CIRCULAR MEMBER FORMED WITH AN AXIAL BORE AND CIRCULAR END PORTIONS OF DIFFERENT DIAMETER EACH DISPOSED SUBSTANTIALLY PERPENDICULAR TO SAID AXIAL BORE, AN EXTERIOR SURFACE HAVING A CONCAVE INDENTATION FORMED ON SAID MEMBER BETWEEN SAID CIRCULAR END PORTIONS, EACH OF SAID CIRCULAR END PORTIONS BEING FORMED WITH A SHALLOW COUNTERBORE, SAID COUNTERBORES HAVING DIAMETERS 